1. Field of the Invention
The present invention relates to a creamy substance container capable of containing a plurality of creamy substances and of simultaneously extruding the plurality of creamy substances and, more specifically, to improvements in an extruding mechanism for a creamy substance container.
2. Description of the Prior Art
A container having a plurality of chambers which are capable of containing a plurality of different kinds of substances and means for simultaneously extruding the plurality of substances is disclosed in Japanese Utility Model Publication (Kokoku) No. 52-7475. This known container comprises a case provided with two longitudinal chambers formed by longitudinally partitioning its interior space, screw shafts longitudinally extended in respective chambers, extrusion plungers each provided with an internally threaded center hole and placed nonrotatably within the respective chambers in screw-engagement with the respective screw shafts, and an operating wheel held in the lower part of the case with a portion thereof protruding outwardly thereof, the wheel being interlocked with the screw shafts. When the operating wheel is rotated by a user, the extrusion plungers are raised simultaneously by the screw shafts.
This known container, however, is intended for containing solid substances and is not suitable for containing creamy substances. If creamy substances would be contained in this known container, they might flow from the upper section of each chamber into the lower section thereof through gaps around the screw shaft or might clog the gaps to hinder the smooth rotation of the screw shaft relative to the extrusion plunger. This means that the raising mechanism for raising the extrusion plungers must be isolated in a liquid-tight fashion from the substances contained in the upper sections of the chambers, and each extrusion plunger must be provided with an internally threaded boss extending downwardly from the lower surface of the extrusion plunger, instead of the threaded center hole, for engagement with the screw shaft. Such a structure requires a space of a volume equal to or greater than the volume of the section for containing the creamy substances above the extrusion plungers, which inevitably increases the size of the container without increasing the capacity for containing the creamy substances.
In order to overcome such disadvantages, one might consider to apply a raising mechanism in a container disclosed in Japanese Utility Model Publication (Kokai) No. 53-521 or 54-11101 to the above known container having plural chambers. Each of these containers is provided with a two-stage raising mechanism comprising a screw shaft provided within a case having a single chamber, a tubular member provided within the case, and an intermediate tubular member provided with an external thread in its outer circumference and with an internal thread in its inner circumference and interposed between the screw shaft and the tubular member. This mechanism can raise the extrusion plunger by a distance twice the distance raised by the mechanism in the Publication No. 52-7475 for the same angle of rotation of the operating wheel. However, since the extrusion plunger is raised by the agency of both the external and internal threads of the intermediate tubular member when the operating wheel is turned, the rise of the extrusion plunger for a fixed angle of rotation of the operating wheel is excessively large, so that it is difficult to control precisely the rise of the extrusion plunger and therefore the amount of discharge of the substance contained in the container.
Such a disadvantage is not a significant problem in extruding a solid material because it can be returned into the container by rotating the operating wheel in the reverse direction when the material is extruded excessively. However, a creamy substance, once extruded, cannot be returned into the container even if the extrusion plunger is retracted from the raised position. Accordingly, in extruding a creamy substance, the operating wheel must be rotated very carefully, and any excessive portion of the extruded creamy substance would be wasted.